Friendship between women:
A woman didn't come home one night.
The next day she told her husband that she had slept over at a friend's house.
The man called his wife's 10 best friends.
None of them knew about it.

Friendship between men:
A man didn't come home one night.
The next day he told his wife that he had slept over at a friend's house.
The woman called her husband's 10 best friends.
8 of them confirmed that he had slept over and 2 of them claimed that he was still there.